Lehmann

Title: Methyl aminolaevulinate–photodynamic therapy: a review of clinical trials in the treatment of actinic keratoses and nonmelanoma skin cancer

Author: Percy Lehmann

Journal Reference: Br J Dermatol. 2007 May;156(5):793-801 (by clicking on this link you will be leaving this site - Galderma is not responsible for the content)

Objective: Review of the current evidence base for the use of methyl aminolevulinate (MAL; Metvix®) PDT in nonmelanoma skin cancer and actinic keratoses (AKs)

Key statements

Dose-ranging studies have established an optimum dose regimen of 160 mg g–1 MAL for 3 h application time.

Basal cell carcinoma (BCC)

  • Complete response rates at 3 months observed with MAL-PDT have been between 85% and 93% with superficial BCC, and between 75% and 82% with nodular BCC.
  • Across 5 studies, recurrence rates for MAL-PDT varied between 7% (‘thin’ nodular BCC in a study with a median follow-up of 35 months) and 22% (primary superficial BCC at 60 months).
  • Cosmetic outcome with MAL-PDT was reported as being ‘good’ or ‘excellent’ by more than 87% of patients or investigators in three non-comparative studies, and in four comparative studies of nodular or superficial BCC.

Bowen’s disease

  • A recent comparative study in Bowen’s disease found that MAL-PDT was associated with a complete response rate of 93% at 3 months
  • MAL-PDT had a superior cosmetic result to cryotherapy in the study, both as assessed by investigators and patients.

Actinic keratoses

  • In two of three studies comparing MAL-PDT with cryotherapy, complete response rate at 3 months was superior with MAL-PDT; the response rates for were 83% for MAL-PDT vs. 72% for cryotherapy, and 91% for MAL-PDT vs. 68% for cryotherapy. In the third study complete response rate at 3 months was 69% for MAL-PDT vs. 75% for cryotherapy. In all three studies, cosmetic outcomes were better with MAL-PDT.
  • In a placebo-controlled study of MAL-PDT in patients with actinic keratoses, cosmetic outcome was rated as either good or excellent by 97% and 91% of investigators and patients, respectively. Seventy-three percent of patients who had undergone other treatments expressed a preference for MAL-PDT.

Conclusions
  • This recent review shows that MAL-PDT has good efficacy across a range of indications.
  • Cosmetic outcome is an important consideration for patients with skin tumours.
  • The principal adverse event associated with photodynamic therapy is pain, but this can be managed relatively easily, and local anaesthetic is not always necessary.
  • MAL-PDT offers the advantages of ‘ambulatory, noninvasive, standardized therapy applied under physician control, with no compliance issues and side-effects limited to a few days… [and] without the complications of scar formation, requirement for grafts, need for repetitive treatments over longer time periods or pigmentary changes’.
  • The review points out again that MAL has higher selectivity and better penetration as compared to ALA.